Research Grade Species #1235
In the 90s I lived in a big duplex in the Boston neighborhood of Brighton, just off of Commonwealth Avenue, the only house on a street with an apartment building and a bunch of medical buildings. The tiny yard was pleasantly neglected by the landlady, and the back of it ended in a low chain link fence looking back into a tangle of even more neglected growth behind the other buildings. I got it into my head that I should learn the plants in my yard--know their names and purposes and natural histories, the way my mom did back in rural Connecticut where I grew up.
One of the plants that caught my eye was a thin climbing vine that wrapped itself around the balusters of our little porch as it stretched up. I was amazed by its flowers: tiny stars with 5 plump points, maybe a quarter inch across, and in a dark purplish brown color--almost black. Later the flowers were replaced with pods the size of small green beans, which dried and split, revealing cottony fluff attached to the seeds.
This plant, like nearly all the plants I ended up identifying in that yard, was an invasive species. It lived a normal existence in the old world, but for one reason or another had ended up in North America, without many of the grazer, parasites, and diseases that made it a normal part of it's life at home. Here in Boston it ran rampant--it runs rampant still--growing and spreading and contributing almost nothing positive to the native ecosystem. In fact, it causes harm. As one can tell by the flowers and fruit, it is in the milkweed family. Monarch butterflies and other insects that specialize on this toxic group of plants will lay their eggs on this species, but their larvae will hatch and find themselves unable or unwilling to thrive on it. In fields cultivated for grazing livestock, this plant will intermingle with the edible grasses and other forage, and the cows and sheep will eschew the whole field. This description is for black swallow-wort, Vincetoxicum nigrum.
It was only in the past few months that I learned that black swallow-wort is not the only plant in its genus that is a recent addition to our landscape. Another Old World milkweed vine is here as well, and today I logged it in iNaturalist for the first time. I had probably walked past it many times dismissing it as the species I already knew. But here is pale swallow-wort V. rossicum, very similar to the other, but with flowers that are light brown. It appears to be more common in the midwest states than in the northeast, and every bit a menace in its adopted continent. Scientists are working on finding insects that will feed on the invaders without attacking North American plants, and experimental releases are underway. This is what it means to be living in interesting times.